Bulletin of the American Physical Society
2021 Fall Meeting of the APS Division of Nuclear Physics
Volume 66, Number 8
Monday–Thursday, October 11–14, 2021; Virtual; Eastern Daylight Time
Session DD: Nuclear Astrophysics I |
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Chair: Amber Lauer-Coles, Brookhaven Room: The Loft |
Tuesday, October 12, 2021 9:30AM - 9:42AM |
DD.00001: Measurement of near-threshold resonance properties in 9B for Big Bang Nucleosynthesis Gordon W McCann, Ingo L Wiedenhoever, Lagy T Baby, Jeff C Blackmon, Catherine M Deibel, Kenneth G Hanselman, Kevin T Macon, Rachel Malecek, Scott T Marley, Balakrishnan Sudarsan The primordial abundance of lithium constitutes the largest discrepancy between the observation of primordial elements and the expectations from Standard Big Bang Nucleosynthesis (SBBN). However, this assumes that the nuclear reactions which could potentially destroy mass-7 nuclei are known to sufficient precision. One of the reactions in question is $^7Be+d \rightarrow 2\alpha + p$. The relevance of the rate for this reaction in SBBN conditions hinges upon the properties of resonances close to the deuteron decay threshold in $^9B$. Using the Super Enge Split-Pole Spectrograph (SESPS) and the Silicon Array for Branching Ratio Experiments (SABRE) at Florida State University, a measurement of $^{10}B(^3He, \alpha)^9B \rightarrow ^7Be+d$ was performed to determine resonance properties of $^9B$ states in the region of interest for SBBN. Results and impact on SBBN will be discussed. |
Tuesday, October 12, 2021 9:42AM - 9:54AM |
DD.00002: Exploring the foundation of nuclear astrophysics via a generative modeling approach to helium fusion reactions Thomas Chen While the field of nuclear astrophysics has recently been a burgeoning area of study and research, there is still a significant portion of information regarding the topic that is not known to science. In particular, while certain foundations of the subject area seem plausible, there is not currently any proof that helium fusion is a key component that drives nuclear astrophysics. In this work, we take an innovative approach by training generative adversarial networks (GANs), which are a machine learning-based algorithm, to model the progression of helium reactions. The cGAN architecture is utilized. We hope that this work will provide insights into the underpinnings of nuclear astrophysics by providing an automated environment for its study. |
Tuesday, October 12, 2021 9:54AM - 10:06AM |
DD.00003: High energy density plasma experiments to study the solar 3He+3He reaction at the NIF and OMEGA lasers Maria Gatu Johnson, Alex B Zylstra, Daniel T Casey, Matthias Hohenberger, Patrick J Adrian, Andrew D Bacher, Benjamin Bachmann, Carl R Brune, Steve Craxton, Warren J Garbett, Emma Garcia, Gerry Hale, Edward P Hartouni, Dean Holunga, Tim M Johnson, Neel Kabadi, Justin H Kunimune, Brandon G Lahmann, Jacob A Pearcy, Heather D Whitley Thermonuclear reaction rates and nuclear processes are explored traditionally in accelerator experiments, which are difficult to execute at conditions relevant to Stellar Nucleosynthesis. High-Energy-Density (HED) plasmas mimic astrophysical environments and can complement accelerator experiments. We describe HED experiments[1,2,3] to study the 3He+3He reaction at the National Ignition Facility (NIF) and OMEGA lasers. Preliminary 3He+3He proton energy spectra measured at center-of-mass (c-m) energies from 60-165 keV indicate that the underlying physics change with c-m energy, with the 5Li ground state resonant peak appearing to decrease in relative importance at higher c-m energy. This is in contrast to measurements of the mirror T+T reaction at c-m energies from 16 to 50 keV, which show the 5He ground state resonant peak being stronger at higher than at lower energy.[4] Challenges with using this platform to determine the reaction rate will also be discussed. |
Tuesday, October 12, 2021 10:06AM - 10:18AM |
DD.00004: An Effective Field Theory and Bayesian Analysis of 3He-alpha scattering Maheshwor Poudel, Daniel R Phillips We consider 3He-alpha scattering in an Effective Field Theory (EFT) built on the separation between the inherent scales in the 7Be and helium systems. We develop the EFT up to next-to-next-to-leading order and construct a statistical model for the uncertainty due to truncation of the theory at that order~\cite{Furnstahl:2015}. We use the resulting formalism to analyze data for recent low energy measurements (0.7-4.0 MeV lab energy) of elastic 3He-alpha scattering obtained using the SONIK gas target at TRIUMF~\cite{Paneruthesis}. |
Tuesday, October 12, 2021 10:18AM - 10:30AM |
DD.00005: Low-background reactions of astrophysical interest with CASPAR Daniel Robertson, Anna Simon, Michael C F Wiescher, Frank Strieder, Thomas Kadlecek, Orlando Gomez, Rebeka Kelmar, Manoel Couder, Alexander C Dombos, August Gula, Shahina Shahina, Mark Hanhardt, Joachim Goerres The broad field of Nuclear Astrophysics considers a wide range of stellar burning processes and nuclear interactions all feeding into the chemical evolution of our Universe. In order to probe such a diverse range of nuclear processes, a complementary set of experimental and theoretical tools must be developed. The profound difficulty in measuring low-energy reactions in the stellar burning regime highlights the need for the development of such techniques. Ongoing advancements consider higher intensity accelerators, more robust and isotopically enriched target material and lower background interference, to name a few. Underground Nuclear Astrophysics facilities such as CASPAR, utilize natural background suppression to extend current experimental data to the lower energies required. New facilities around the world are coming on-line with a view to capitalizing on underground cosmic ray suppression, each offering unique techniques and capabilities. This talk will highlight recent and future CASPAR campaigns incorporting above and below ground measurements of reactions including 18O(a,g), 22Ne(a,n) and 22Ne(a,g). |
Tuesday, October 12, 2021 10:30AM - 10:42AM |
DD.00006: 14N(p,γ)15O – the source of the solar CNO neutrino flux Michael C F Wiescher, Ani Aprahamian, Richard J deBoer, Bryce Frentz, Joachim Goerres, Dan Robertson BOREXINO has recently measured for the first time the flux of neutrinos from the decay of radioactive 15O in the solar core, providing a unique and direct way to determine the solar metallicity. The CNO neutrino flux depends directly on the solar 15O abundance, which in turn is determined by the 14N(p,γ)15O reaction rate at solar temperatures. This reaction rate relies largely on the extrapolation of the experimentally obtained reaction cross section data towards solar energies. This extrapolation carries significant uncertainties due to the complex interference patterns near the particle threshold in 15O, which in turn translates into a substantial uncertainty for a reliable prediction of the solar metallicity. We will present new data on low energy measurements at the CASPAR underground accelerator laboratory and lifetime measurements of 15O threshold states at the Nuclear Science Laboratory at Notre Dame to yield a much improved prediction for the reaction rate at solar temperatures and therefore a more reliable prediction for the solar metallicity to be compared with the BOREXINO data. |
Tuesday, October 12, 2021 10:42AM - 10:54AM |
DD.00007: The study of the $^{17}F(\alpha,p)^{20}Ne reaction rate using the ANASEN Active target detector Vignesh Sitaraman
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Tuesday, October 12, 2021 10:54AM - 11:06AM |
DD.00008: Measuring the cross section of the 15N(a,g)19F reaction using a single-fluid bubble chamber. David Neto, Melina Avila, Kevin Bailey, Jay F Benesch, Brandi Cade, Brad J DiGiovine, Joseph M Grames, Alicia Hofler, Roy J Holt, Reza Kazimi, Dave Meekins, Michael McCaughan, Daniel Moser, Matthew Poelker, Thomas O'Connor, Karl E Rehm, Seamus P Riordan, Riad S Suleiman, Rashi Talwar, Claudio Ugalde
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Tuesday, October 12, 2021 11:06AM - 11:18AM |
DD.00009: Interference effects due to sub-threshold resonances in the 18F destruction reaction 18F(p,α)15O at nova temperatures Federico E Portillo Chaves, Kiana Setoodehnia, Caleb A Marshall, Richard Longland The discrepancy between observed and predicted 18F abundances in classical nova explosions is still one of the main problems studied in nuclear astrophysics. This mismatch is mainly caused by uncertainties in the cross sections used in the input of nova computational models, especially in the 18F main destruction reaction 18F(p,α) 15O at low energies, hence placing a poor constraint on the 18F abundances predicted by those models. The main source of these uncertainties is the incomplete knowledge of interference effects between broad resonances (e.g. ECM = 665 keV and ECM = 1380 keV) and those near the proton-threshold region. Accurately determining the energies, spin-parities (Jπ), and ANC (widths) of sub-threshold (unbound) states is crucial to study these interference effects. In this talk we will show the results of a 20Ne( 3He,α)19Ne neutron pickup reaction performed at the Triangle Universities Nuclear Laboratory using its high resolution Enge split-pole magnetic spectrograph. We will present new values and a new compilation for energies of excited states in 19Ne ranging from 1 to 8 MeV. We will also show the results obtained for the Jπ of the proton sub-threshold states in 19Ne at 6.290 MeV state (ECM = -120 keV) and at 6.132 MeV state (ECM = -278 keV). Finally, we will provide new reaction rates for the 18F(p,α)15O reaction that include these interference effects at nova temperatures. |
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